Change material on multiple (different) objects simultaneously
Not exactly, no. But there a few workarounds.

Object Groups

You can quickly copy the materials from the active object to all selected objects with &#9096; CtrlL> Materials.

Combining that with groups, you can "store" selections of objects for later. Group the selected objects together with &#9096; CtrlG, then update the materials of the group by activating the object with the updated materials and pressing &#8679; ShiftG (to reselect the group) then &#9096; CtrlL> Materials.

Node Groups

I know you specifically asked about switching materials and not about altering a single material. However, if you relax that constraint a bit you can use node groups to achieve this. Put the entirety of your material in a node group (A to select all nodes, then &#9096; CtrlG), and voila:



Note that in this example, the objects have separate materials: "Material A" and "Material B". They could instead share the same material, or have multiple materials each, some shared and some not. The link is through the node group.